Image Sensor Multiple Readout Paths Dynamic Range
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Solution Overview
Problem
CMOS image sensors face limitations in dynamic range and noise reduction due to the complexity and power consumption of high bit depth analog-to-digital converters (ADCs) required for high performance, which increases costs and semiconductor die area.
Innovation Solution
The use of multiple readout circuit paths with different amplification responses and 10-bit ADCs in each path, allowing for the generation of digital image samples at a higher bit depth without the need for complex column readout circuits, enabling a higher dynamic range while reducing power consumption and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high bit depth ADCs are used to achieve high dynamic range, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent divides the readout circuit into multiple parallel paths with different bit depths (e.g., two 10-bit ADCs instead of one 14-bit ADC). Each path processes a portion of the dynamic range, and the results are combined to achieve the full dynamic range. This segmentation reduces the complexity of individual components while maintaining overall performance.
Solution Approach 2:
The patent transitions from a single high-bit-depth ADC to multiple lower-bit-depth ADCs operating in parallel. This dimensional change from one-dimensional sequential conversion to multi-dimensional parallel conversion enables achieving high dynamic range through combination of multiple simpler paths.
2Measurement precision
If high bit depth ADCs are used to achieve high dynamic range, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent segments the high dynamic range measurement task into multiple parallel paths with lower bit depth ADCs. Each ADC consumes less power individually, and the total power consumption is distributed across multiple simpler circuits rather than concentrated in one complex high-bit-depth converter.
3Measurement precision
If high bit depth ADCs are used to achieve high dynamic range, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent uses multiple lower-bit-depth ADCs that are simpler and less expensive to manufacture than a single high-bit-depth ADC. The reduced complexity of each individual ADC translates to lower manufacturing costs while achieving the same overall dynamic range through parallel processing.
4Measurement precision
If multiple readout circuit paths with different amplification responses are used, then dynamic range is improved, but device complexity increases
Solution Approach 1:
The patent segments the readout function into multiple parallel circuit paths, each with specific amplification characteristics suited for different portions of the dynamic range. This segmentation allows optimized performance across the full range while keeping each individual path relatively simple.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for a higher dynamic range comparable to high bit depth ADCs, such as 14-bit, using simpler and less expensive circuitry, achieving a 14-bit dynamic range with two 10-bit ADCs and smaller capacitors, thereby reducing the gap with CCD image sensors in terms of cost and complexity.
Implementation Method 1
The photodetector converts the incident light into an electrical charge
Data Source
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AI summary
An image sensor apparatus comprises an image sensor for generating digital images having a high dynamic range. The image sensor apparatus includes an image sensor for generating a first and a second set of digital image samples at a first bit depth, with each set of digital image samples generated by a different column readout circuit path. A processor combines the first and second set of digital image samples to generate a digital image at a second bit depth, the second bit depth higher than the first bit depth.